The extra "junk" are front sight inserts used to create a comfortable sight picture when shooting at bulls eye targets. Depending on your distance, target type and eyes you should be able to find an insert that will give you a sharp image.

The extra rear iris assortment is to allow the shooter to switch according to light conditions. In general a 1.1 is the standard and I believe the smallest of them is a 1.1. If it is bright and sunny, use that one. If you are in a match and the weather is bad and heavy clouds, you need a larger rear aperture to let in more light. Personally, I have only shot in one match where the skies got so dark that I needed a larger front and rear aperture and NOBODY who is pleasure shooting would have continued to shoot that day. We were soaked to the bone. It's unlikely you will ever need to use those larger irises.
The rifle and the sights are intended for small bore competition using the A23-5 @50 yds, the A50 @ 50 meters(only in metric or international matches), A26 @50 meters in NRA conventional matches and the A25 @ 100 yds and the A33 for 100 meters in metric events.
The sight picture should be a series of PERFECT concentric circles. You want to look through the rear aperture and see the front globe perfectly centered with an equal amount of light around the globe with the bull PERFECTLY centered in the front sight insert with equal white all around the bull.
I dryfire mine by using spent cases. Save some of your brass. It is a bit of a pain to load spent brass so I will generally dryfire 5 shots on one case which means that I lift the bolt and then push it back down which is enough to cock the bolt but I don't eject the case.

BTW, I'm using my Anschutz rear sight on my CM-2 so that I can use my adjustable rear iris and I usually have it down to somewhere between .8 and
.9.
The front sight insert selection is inadequate and I suggest you get some plastic inserts. If you do this you are going to need to put some black tape over the slot on top of the globe to prevent light from getting to the edge of the plastic insert. I've used 3.0, 3.2, currently using 3.4 and this afternoon considered trying a 3.6 on my next trip to the range.
I've been "Squintin' Tarantino" long enough and have learned the importance of using an occluder over my non aiming eye and keeping both eyes open. The sight picture is really improved but when shooting this afternoon I wanted more white around the bull. You just have to shoot with each size to determine what works best for you. Some of the best olympic shooters want just a sliver of white aound the bull, and some others like lots of white. I think it depends on YOUR eyes what you will shoot best with.

My two Izhmash built rifles shoot Dynapoints very well when the temp. is cool out.
All targets shot with Iron sights off a bench rest...I wish I could do that prone....Someday.
I am very reluctant too shoot my hi-dollar ammo being a rookie with iron sights.
The Vel. of Win. Dyno's are very close to super sonic -sub-sonic...so some times
you will get a few super sonic cracks Dependant on the temp.

The rising cost of ammunition is making me want to find a cheaper practice ammo. I've been using SK Std Plus for practice and SK Match for competition but with the switch to Eley I need a cheaper practice ammo. I have a few boxes of Dynapoint and Expert that I'm going to see if I can get some benefit from as a practice ammo.
Shooting prone is a very demanding discipline and the best thing you can do is just spend the time in position shooting. The very best prone shooters are very detail oriented and I'm not so much.
Nice targets Swiss!